1. Field of the Invention
Embodiments of the present invention generally relate to correction of projector-camera misalignment in structured light systems.
2. Description of the Related Art
In structured light imaging systems, a projector-camera pair is used to estimate the three-dimensional (3D) depth of a scene and shape of objects in the scene. The principle behind structured light imaging is to project patterns on objects/scenes of interest and capture images with the projected pattern. The depth is estimated based on variations of the captured pattern in comparison to the projected pattern. In such imaging systems, the relative position of the camera with respect to the projector is typically fixed and the camera-projector pair is initially calibrated, e.g., by the maker of the system or by a user following calibration instructions.
After physical calibration, a further step involving projecting a checker board pattern on a plane surface at different depths may be required. Note that this calibration may require that the projector has the capability to project more than one pattern. Calibration is performed by finding correspondences between locations of corners of the checkerboard pattern in captured and projected images. Such calibration may require manual intervention in which the plane surface is moved by the user in front of the camera-projector pair. This calibration is generally performed once as the assumption is that there will be no change in the relative position of the camera-projector pair.
Such calibration is generally sufficient as long as the camera-projector pair remains stationary. However, in practical applications, a structured light system may not be stationary. For example, a structured light system may be mounted on an unstable platform or used in a handheld device. In such applications, the relative position of the camera and projector can be altered unintentionally over time or due to manufacturing imperfections and environmental factors, thus necessitating re-calibration.